Delving deeper into molecular markers, breast cancer can be categorized into Luminal A type, Luminal B type, HER-2 overexpression type, and Triple-Negative type, determined by the expression levels of ER, PR, HER-2, and Ki-67 (Gangrade et al., 2018; Fumagalli and Barberis, 2021; Liu H. Y. et al., 2022). The gene discussed is ESR1; the disease is breast cancer.